Gravesande, Willem Jacob 's
,
An essay on perspective
Text
Text Image
Image
XML
Thumbnail overview
Document information
None
Concordance
Notes
Handwritten
Figures
Content
Thumbnails
List of thumbnails
<
1 - 10
11 - 20
21 - 30
31 - 40
41 - 50
51 - 60
61 - 70
71 - 80
81 - 90
91 - 100
101 - 110
111 - 120
121 - 130
131 - 140
141 - 150
151 - 160
161 - 170
171 - 180
181 - 190
191 - 200
201 - 210
211 - 220
221 - 230
231 - 237
>
131
(62)
132
(63)
133
(64)
134
135
136
137
(65)
138
(66)
139
(67)
140
(68)
<
1 - 10
11 - 20
21 - 30
31 - 40
41 - 50
51 - 60
61 - 70
71 - 80
81 - 90
91 - 100
101 - 110
111 - 120
121 - 130
131 - 140
141 - 150
151 - 160
161 - 170
171 - 180
181 - 190
191 - 200
201 - 210
211 - 220
221 - 230
231 - 237
>
page
|<
<
(91)
of 237
>
>|
<
echo
version
="
1.0RC
">
<
text
xml:lang
="
en
"
type
="
free
">
<
div
xml:id
="
echoid-div330
"
type
="
section
"
level
="
1
"
n
="
179
">
<
p
>
<
s
xml:id
="
echoid-s2068
"
xml:space
="
preserve
">
<
pb
o
="
91
"
file
="
0159
"
n
="
184
"
rhead
="
on PERSPECTIVE.
"/>
in the Perpendicular R S, continued equal to R S,
<
lb
/>
and draw f i parallel to the Baſe Line, in which
<
lb
/>
take the Point f in E I, the ſame as F in F I ; </
s
>
<
s
xml:id
="
echoid-s2069
"
xml:space
="
preserve
">
<
note
symbol
="
*
"
position
="
right
"
xlink:label
="
note-0159-01
"
xlink:href
="
note-0159-01a
"
xml:space
="
preserve
">110.</
note
>
if the Threads which before were faſten’d in F,
<
lb
/>
being placed in f, and by uſing them thus faſten’d,
<
lb
/>
as likewiſe S Q for a Baſe Line, the Repreſen-
<
lb
/>
tations of the Feet of the Perpendiculars be
<
lb
/>
found , you will have the Repreſentations
<
note
symbol
="
*
"
position
="
right
"
xlink:label
="
note-0159-02
"
xlink:href
="
note-0159-02a
"
xml:space
="
preserve
">110.</
note
>
their Extremities.</
s
>
<
s
xml:id
="
echoid-s2070
"
xml:space
="
preserve
"/>
</
p
>
</
div
>
<
div
xml:id
="
echoid-div332
"
type
="
section
"
level
="
1
"
n
="
180
">
<
head
xml:id
="
echoid-head192
"
style
="
it
"
xml:space
="
preserve
">The Demonſtration of the two laſt Ways.</
head
>
<
p
>
<
s
xml:id
="
echoid-s2071
"
xml:space
="
preserve
">114. </
s
>
<
s
xml:id
="
echoid-s2072
"
xml:space
="
preserve
">If a Plane be imagined to paſs through
<
lb
/>
<
note
position
="
right
"
xlink:label
="
note-0159-03
"
xlink:href
="
note-0159-03a
"
xml:space
="
preserve
">Fig. 60,
<
lb
/>
and 61.</
note
>
the Extremities of the equal Perpendiculars, it
<
lb
/>
will be parallel to the Geometrical Plane, and
<
lb
/>
will meet the perſpective Plane in S Q; </
s
>
<
s
xml:id
="
echoid-s2073
"
xml:space
="
preserve
">becauſe
<
lb
/>
R S is equal to the ſaid Perpendiculars: </
s
>
<
s
xml:id
="
echoid-s2074
"
xml:space
="
preserve
">Moreover,
<
lb
/>
the Extremities of theſe Perpendiculars form a
<
lb
/>
Figure in this ſuppoſed Plane, ſimilar to that
<
lb
/>
which their Feet form in the Geometrical Plane;
<
lb
/>
</
s
>
<
s
xml:id
="
echoid-s2075
"
xml:space
="
preserve
">and the ſaid Figure hath the ſame Situation with
<
lb
/>
regard to the Line Q S, as that on the Geome-
<
lb
/>
trical Plane hath in reſpect of H R: </
s
>
<
s
xml:id
="
echoid-s2076
"
xml:space
="
preserve
">And conſe-
<
lb
/>
quently, if the Figure in the Geometrical Plane
<
lb
/>
be ſo raiſed up, that it hath the ſame Reſpect to
<
lb
/>
Q S, as it had to H R, and if the Appearances
<
lb
/>
of the Feet of the propoſed Perpendiculars be
<
lb
/>
found, the Repreſentations of their Extremties
<
lb
/>
will be had. </
s
>
<
s
xml:id
="
echoid-s2077
"
xml:space
="
preserve
">But the before ſuppoſed Tranſpo-
<
lb
/>
ſition of the Figure in the Geometrical Plane,
<
lb
/>
gives it the requiſite Situation with regard to
<
lb
/>
Q S, and the Repreſentation of the Figure
<
lb
/>
conſider’d in this new Geometrical Plane is
<
lb
/>
found ; </
s
>
<
s
xml:id
="
echoid-s2078
"
xml:space
="
preserve
">becauſe S Q, is taken for the Baſe
<
note
symbol
="
*
"
position
="
right
"
xlink:label
="
note-0159-04
"
xlink:href
="
note-0159-04a
"
xml:space
="
preserve
">32, 39.</
note
>
O f (Fig. </
s
>
<
s
xml:id
="
echoid-s2079
"
xml:space
="
preserve
">60.) </
s
>
<
s
xml:id
="
echoid-s2080
"
xml:space
="
preserve
">equal to the Height of the Eye
<
lb
/>
above this Plane, and fi (Fig. </
s
>
<
s
xml:id
="
echoid-s2081
"
xml:space
="
preserve
">61.) </
s
>
<
s
xml:id
="
echoid-s2082
"
xml:space
="
preserve
">is the Geo-
<
lb
/>
metrical Line in the ſaid Plane.</
s
>
<
s
xml:id
="
echoid-s2083
"
xml:space
="
preserve
"/>
</
p
>
</
div
>
</
text
>
</
echo
>